Many petroleum products, and some non-petroleum materials, are used as lubricants and the correct operation of the equipment depends upon the appropriate viscosity of the liquid being used. In addition, the viscosity of many petroleum fuels is important for the estimation of optimum storage, handling, and operational conditions. Thus, the accurate determination of viscosity is essential to many product specifications.

Density is a fundamental physical property that can be used in conjunction with other properties to characterize both the light and heavy fractions of petroleum and petroleum products.

Determination of the density or relative density of petroleum and its products is necessary for the conversion of measured volumes to volumes at the standard temperature of 15°C.

1.1 This test method specifies a procedure for the concurrent measurement of both the dynamic viscosity, η, and the density, ρ, of liquid petroleum products and crude oils, both transparent and opaque. The kinematic viscosity, ν, can be obtained by dividing the dynamic viscosity, η, by the density, ρ, obtained at the same test temperature.

1.2 The result obtained from this test method is dependent upon the behavior of the sample and is intended for application to liquids for which primarily the shear stress and shear rate are proportional (Newtonian flow behavior).

1.3 While the precision has only been determined for base oils in the viscosity range from 2.05 to 456 mPa·s at 40°C and from 0.83 to 31.6 mPa·s at 100°C and in the density range from 0.82 to 0.92 g/mL at 15°C (see 15.4), the test method can be applied to a wider range of materials, viscosity, density, and temperature. For materials not listed in Precision and Bias (Section 15), the precision and bias may not be applicable.

1.4 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard. The accepted units of measure for density are grams per millilitre (g/mL) or kilograms per cubic metre (kg/m³).

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.